This invention relates generally to engine-driven, electrical generators, and in particular, to a method of cooling engine coolant flowing through a radiator of an engine-driven, electrical generator.
Engine-driven, electrical generators are used in a wide variety of applications. Typically, such electrical generators utilize a single driving engine directly coupled to a generator or alternator through a common shaft. Upon actuation of the engine, the crankshaft thereof rotates the common shaft so as to drive the alternator which, in turn, generates electricity. It can be appreciated that since the engine and the alternator are housed in a single enclosure, a significant amount of heat is generated within the enclosure during operation of the electrical generator.
Heretofore, in order to cool the components of a prior electrical generator, louvers were provided in the walls of the enclosure thereof. A fan, coupled to the crankshaft of the engine, rotates during operation of the electrical generator. The rotating fan draws air into the enclosure through the louvers in the walls and blows air over the components of the electrical generator, including the engine, the alternator, and the radiator. In such a manner, it is intended that the air passing over the components of the electrical generator have a cooling effect on the components during their operation such that the temperatures of the components are maintained below safe operating limits.
While functional under certain conditions, air flow arrangements of prior electrical generators have significant limitations. Typically, the fan used to cool the radiator is rotated at a predetermined, constant speed. It can be appreciated that during start-up of the electrical generator, the temperature of the engine coolant flowing through the radiator is at a minimum. As such, it is unnecessary to rotate the fan at full speed in order to cool the engine coolant flowing through the radiator. As the engine of the electrical generator approaches full operating power, the temperature of the engine coolant flowing through the radiator increases. Consequently, it becomes necessary for the rotational speed of the engine fan to increase in order for the engine fan to adequately cool the engine coolant flowing through the radiator. As such, it is highly desirable to provide a fan drive structure which provides greater cooling of the radiator as the temperature of the coolant flowing therethrough increases.
Therefore, it is a primary object and feature of the present invention to provide a method of cooling the engine coolant flowing through a radiator of an engine-driven, electrical generator that improves the overall operating efficiency of the same.
It is a further object and feature of the present invention to provide a method of cooling the engine coolant flowing through a radiator of an engine-driven, electrical generator that more economically cools the engine coolant of the electrical generator than prior methods.
It is a still further object and feature of the present invention to provide a method of cooling the engine coolant flowing through a radiator of an engine-driven, electrical generator that is simple and inexpensive to implement.
In accordance with the present invention, a method is provided of cooling the engine coolant flowing through a radiator. The method includes the step of monitoring a temperature of coolant flowing through the radiator. A fan is positioned adjacent to the radiator and rotates at a predetermined speed. The speed of the fan is varied in response to the temperature of the coolant.
The method includes the additional step of supporting the fan on a rotatable fan shaft having a driven pulley attached thereto. The driven fan pulley includes a groove formed therein. A drive pulley is also provided. The drive pulley has a groove formed therein which has a predetermined depth. A fan belt is positioned about the groove of the driven fan pulley and the groove of the drive pulley such that rotation of the drive pulley is translated to the driven fan pulley by the fan belt. The step of varying the speed of the fan includes the additional step of varying the depth of the groove in the drive pulley. The depth of the groove in the drive pulley is decreased to increase the speed of the fan and the depth of the groove in the drive pulley is increased to decrease the speed of the fan.
In accordance with a further aspect of the present invention, a method is provided for cooling engine coolant flowing through a radiator operatively connected to an engine. The method includes the steps of positioning a fan adjacent the radiator for generating an air flow through the radiator and starting the engine. Thereafter, the fan is rotated at a first, or low speed. The temperature of the engine coolant flowing through the radiator is monitored. The fan is rotated at a second, high speed in response to the temperature of the engine coolant exceeding a threshold.
It is contemplated to mount the fan on a rotatable fan shaft and to operatively connect the fan shaft to a drive shaft via fan drive system. The fan drive system includes first and second fan pulleys interconnected to the fan shaft. Each fan pulley has a groove therein for receiving a corresponding fan belt. First and second drive pulleys are interconnected to the drive shaft. Each drive pulley has a groove therein for receiving a corresponding drive belt. A variable pitch drive sheave assembly is movable between a first high speed position wherein the fan is rotated at the high speed and a second low speed position wherein the fan is rotated at the low speed. The variable pitch sheave assembly includes first and second drive belt grooves. The drive belt grooves have a first depth with the variable pitch sheave assembly in the high speed position and a second depth with the variable pitch sheave assembly in the low position. In addition, the variable pitch sheave assembly includes first and second fan belt grooves. The fan belt grooves have a first depth with the variable pitch sheave assembly in the high speed position and a second depth with the variable pitch assembly in the low speed position. The fan drive system also includes first and second drive belts seated in corresponding drive belt grooves in a variable pitch sheave assembly and in corresponding grooves in the drive pulleys to translate rotation of the drive pulleys to the variable pitch sheave assembly. First and second fan belts are seated in corresponding fan belt grooves in the variable pitch sheave assembly and in corresponding grooves in the fan pulleys to translate rotation of the variable pitch sheave assembly to the fan pulleys.
It is contemplated that the variable pitch sheave assembly also include a rotatable sheave shaft having first and second opposite ends. A first outer member is affixed to the first end of the sheave shaft and a second outer member is affixed to the second end of the sheave shaft. An intermediate member is affixed to the sheave shaft between the first and second ends thereof. A first slidable member slides along the sheave shaft between the first outer member and the intermediate member. The first slidable member and the first outer member define the first drive belt groove therebetween. The first slidable member and the intermediate member define the first fan belt groove therebetween. A second slidable member is slidable along the sheave shaft between the intermediate member and the second outer member. The second slidable member and the second outer member define the second drive belt groove therebetween. The second slidable member and intermediate member define a second fan belt groove therebetween. It is contemplated that the first depth of the drive belt grooves is greater than the second depth of the drive belt grooves and the first depth of the fan belt grooves is less than the second depth of the fan belt grooves.
The method further includes the steps of operatively connecting an actuator to the variable pitch sheave assembly and moving the variable pitch sheave assembly with the actuator between the high speed position and the low speed position. In addition, the step of monitoring the temperature of the engine coolant includes the step of operatively connecting a controller to the radiator. The controller controls operation of the actuator in response to the temperature of the engine coolant.
Alternatively, the method includes the steps of supporting the fan on a rotatable fan shaft having a driven fan pulley attached thereto. The driven fan pulley includes a groove formed therein. A drive pulley having a groove formed therein is also provided. The groove has a predetermined depth. A fan belt is positioned about the groove of the driven fan pulley and the groove of the drive pulley such that the rotation of the drive pulley is translated to the driven fan pulley by the fan belt. The depth of the groove in the drive pulley when the fan is rotating at the lower speed is greater than the depth of the groove in the drive pulley when the fan is rotating at the high speed.
In accordance with a further aspect of the present invention, a method is provided for cooling the engine coolant flowing through a radiator operatively connected to an engine. The method includes the step of supporting a fan on a rotatable fan shaft having a driven fan pulley attached thereto. The driven fan pulley includes a groove formed therein. The fan is positioned adjacent the radiator and a drive pulley having a groove formed therein is provided. The groove in the drive pulley has a predetermined depth. A fan belt is positioned about the groove of the driven fan pulley and the groove of the drive pulley such that rotation of the drive pulley is translated to the driven fan pulley by the fan belt. The fan is rotated at a predetermined speed and the temperature of the engine coolant flowing through the radiator is monitored. The depth of the groove in the drive pulley is varied in order to vary the speed of the fan.
The step of varying the speed of the groove in the drive pulley includes the steps of decreasing the depth of the groove in the drive pulley to increase the speed of the fan and increasing the depth of the groove in the drive pulley to decrease the speed of the fan. The predetermined speed of the fan is an initial speed. The speed of the rotation of the fan is increased in response to the temperature of the engine coolant exceeding a threshold. Alternatively, the speed of the rotation of the fan is decreased in response to the temperature of the engine coolant dropping below the threshold.